+ mm-khugepaged-count-collapses-where-khugepaged-makes-them.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/khugepaged: count collapses where khugepaged makes them
has been added to the -mm mm-unstable branch.  Its filename is
     mm-khugepaged-count-collapses-where-khugepaged-makes-them.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-khugepaged-count-collapses-where-khugepaged-makes-them.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Kiryl Shutsemau (Meta)" <kas@kernel.org>
Subject: mm/khugepaged: count collapses where khugepaged makes them
Date: Wed, 16 Sep 2026 10:31:29 +0100

collapse_single_pmd() bumps khugepaged_pages_collapsed for its caller, and
tests cc->is_khugepaged to know whether it should: the counter belongs to
the daemon, and MADV_COLLAPSE must not touch it.

The daemon sees every result of every collapse it asks for, so it can keep
its own counter without the shared path testing who called.

Assisted-by: LLM
Link: https://lore.kernel.org/20260916093145.4022188-3-kirill@shutemov.name
Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
---

 mm/khugepaged.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

--- a/mm/khugepaged.c~mm-khugepaged-count-collapses-where-khugepaged-makes-them
+++ a/mm/khugepaged.c
@@ -2808,10 +2808,8 @@ static enum scan_result collapse_single_
 
 	mmap_assert_locked(mm);
 
-	if (vma_is_anonymous(vma)) {
-		result = collapse_scan_pmd(mm, vma, addr, lock_dropped, cc);
-		goto end;
-	}
+	if (vma_is_anonymous(vma))
+		return collapse_scan_pmd(mm, vma, addr, lock_dropped, cc);
 
 	file = get_file(vma->vm_file);
 	pgoff = linear_page_index(vma, addr);
@@ -2847,9 +2845,6 @@ retry:
 			result = SCAN_SUCCEED;
 		mmap_read_unlock(mm);
 	}
-end:
-	if (cc->is_khugepaged && result == SCAN_SUCCEED)
-		++khugepaged_pages_collapsed;
 	return result;
 }
 
@@ -2926,6 +2921,8 @@ static void collapse_scan_mm_slot(unsign
 
 			*result = collapse_single_pmd(khugepaged_scan.address,
 						      vma, &lock_dropped, cc);
+			if (*result == SCAN_SUCCEED)
+				khugepaged_pages_collapsed++;
 			/* move to next address */
 			khugepaged_scan.address += HPAGE_PMD_SIZE;
 			if (lock_dropped)
_

Patches currently in -mm which might be from kas@kernel.org are

mm-huge_memory-do-not-touch-frozen-folios-in-deferred_split_isolate.patch
mm-huge_memory-dequeue-the-deferred-split-after-the-split-freeze.patch
mm-huge_memory-add-folio_reset_partially_mapped.patch
mm-khugepaged-drop-redundant-mm_struct-pin-in-madvise_collapse.patch
mm-khugepaged-count-collapses-where-khugepaged-makes-them.patch
mm-khugepaged-rename-mthp_present_ptes-bitmap-to-eligible_ptes.patch
mm-collapse-add-collapseh-for-the-collapse-interface.patch
mm-collapse-state-what-a-collapse-may-do-in-the-policy.patch
mm-collapse-drop-the-collapse_possible-wrapper.patch
mm-collapse-name-the-per-table-scan-reset-for-what-it-resets.patch
mm-collapse-separate-scanning-a-pte-table-from-collapsing-it.patch
mm-collapse-open-code-collapse_single_pmd-in-its-two-callers.patch
mm-collapse-work-out-the-orders-a-vma-allows-once-per-vma.patch
mm-collapse-declare-the-collapse-interface-in-collapseh.patch
mm-collapse-implement-madv_collapse-in-madvisec.patch